The present invention relates to a display, and more particularly to a display system having a non-luminescent display device such as a liquid crystal display and a light source, and a method of illumination to a display area of the non-luminescent display device.
Non-luminescent display devices such as liquid crystal displays have been used as thin display devices, wherein the display forms images which are displayed with illuminations. The following methods for illuminations have been available.
The first illumination method is as illustrated in FIG. 1 which is a fragmentary cross sectional elevation view illustrative of a reflection of a natural light by a reflecting plate on a bottom of a display device A display device 101 has a display surface and a back surface facing to a reflecting plate 103. A natural light 111 is incident from the display surface into the display device 101 at an oblique angle to the display surface The incident light 111 reaches a surface of the reflecting plate 103 and is then reflected thereby. The reflected light is transmitted through the display device 101.
The above first illumination method has the following problems. This method utilizes only the natural light, for which reason this first conventional method is inapplicable to a dark place or a weak natural light place The natural light is attenuated upon transmission thereof through the non-luminescent display device. As described above, the natural light is incident into the non-luminescent display device and then reflected by the reflecting plate before the reflected light is further transmitted through the non-luminescent display device, for which reason the natural light is attenuated two times, whereby it is difficult to obtain a sufficient intensity of the display light.
The second illumination method is as illustrated in FIG. 2 which is a fragmentary cross sectional elevation view illustrative of a transmission of an illumination light from an opposite surface to a display surface of a display device. A light source 102 is positioned to face an opposite surface to a display surface of a display device so that an illumination light 112 as emitted from the light source 102 is transmitted from the opposite surface to the display surface of the display device 101.
The above second illumination method has the following problems, This method requires the light source to always remain ON for obtaining a sufficient intensity of the display light, for which reason it is difficult to respond to the requirement for a possible reduction in a power consumption of the display.
The third illumination method is as illustrated in FIG. 3 which is a fragmentary cross sectional elevation view illustrative of a combination of the above first and second methods, wherein a reflecting plate 103 is provided on an opposite surface to a display surface of a display device 101 and a light surface 102 is positioned in a back side of the reflecting plate 103, so that a natural light 111 is incident from the display surface into the display device 101 at an oblique angle to the display surface. The incident light 111 reaches a surface of the reflecting plate 103 and is then reflected thereby. The reflected light 111 is transmitted through the display device 101. Further, an illumination light 112 as emitted from the light source 102 is transmitted from the opposite surface to the display surface of the display device 101. The reflecting plate 103 is semi-transparent to the light so that the reflecting plate 103 is capable of reflecting the natural light 111 and also allowing the illumination light 112 to be transmitted through the reflecting plate 103.
The above third illumination method has the following problems. The light reflecting plate is semi-transparent for responding to the conflict requirements for transmission of the illumination light through the light reflecting plate and reflection of the natural light by the light reflecting plate. This means it difficult to obtain high reflectivity and transparency. The efficiency in use of the illumination and the natural light is low The display can not exhibit such the required high display performance.
The fourth illumination method is as illustrated in FIG. 4 which is a fragmentary cross sectional elevation view illustrative of another combination of the above first and second methods, wherein combined two multiple window plates 603 are provided on an opposite surface to a display surface of a display device 101 and a light surface 102 is positioned in a back side of the combined two multiple window plates 603. Each of the combined two multiple window plates 603 has windows. The two multiple window plates 603 are allowed to be displaced from each other or relatively move to each other so that the individual multiple windows of the two multiple window plates 603 are alternately positioned, whereby no overlap is formed between the individual multiple windows of the two multiple window plates 603, and also so that the individual multiple windows of the two multiple window plates 603 are aligned, whereby overlaps are formed between the individual multiple windows of the two multiple window plates 603, thereby forming windows penetrating the two multiple window plates 603. A natural light 111 is incident from the display surface into the display device 101 at an oblique angle to the display surface. The incident light 111 reaches a surface of the combined two multiple window plates 603 and is then reflected thereby, wherein the combined two multiple window plates 603 are displaced from each other so that the individual multiple windows of the two multiple window plates 603 are alternately positioned, whereby no overlap is formed between the individual multiple windows of the two multiple window plates 603, thereby forming no window penetrating the two multiple window plates 603. The reflected light 111 is then transmitted through the display device 101. Further, an illumination light 112 as emitted from the light source 102 is transmitted through the two multiple window plates 603 and then through the display device 101, wherein the combined two multiple window plates 603 are displaced from each other so that the individual multiple windows of the two multiple window plates 603 are aligned, whereby overlaps are formed between the individual multiple windows of the two multiple window plates 603, thereby forming windows penetrating the two multiple window plates 603 in order to allow the illumination light 112 to be transmitted through the overlapped windows of the two multiple window plates 603. This conventional method is disclosed in Japanese laid-open utility model publication No 59-194781.
The above fourth illumination method has the following problems. The multiple windows of the two multiple window plates 603 are defined by grids. Namely, the body of each of the two multiple window plates 603 comprises grids which define the windows Even if the two multiple window plates 603 are displaced so that the individual windows of the two multiple window plates 603 are just overlapped, then the illumination light is partially shielded by this grid portion. This means it difficult to improve the efficiency in use of the illumination light. Further, a driver and a controller are required to relatively move the two multiple window plates 603 under precise controls in position Actually, a system having the driver and the controller is required to be provided, whereby another problem with increase in the cost is also raised.
The fifth illumination method is as illustrated in FIG. 5 which is a fragmentary cross sectional elevation view illustrative of still another combination of the above first and second methods, wherein a reflecting flexible thin film 103 is provided on an opposite surface to a display surface of a display device 101 and a light surface 102 is positioned in a back side of the reflecting flexible thin film 103 The reflecting flexible thin film 103 can be wound and leaded, so as to adjust the reflection and transmission of the natural light. This conventional method is disclosed in Japanese laid-open patent publication No. 5-80328.
The above fifth illumination method has the following problems. The reflecting flexible thin film 103 is wound and leaded. This means it required to provide a system for wining and leading the reflecting flexible thin film 103 under precise control whereby another problem with increase in the cost is also raised.
The sixth illumination method is as illustrated in FIG. 6 which is a fragmentary cross sectional elevation view illustrative of a sixth conventional non-luminescent display device, wherein a light source and an optical guide 11 are provided. The optical guide 11 is plate-shaped and positioned so as to cover an entire of a displaying surface of the non-luminescent device. The light source 12 is positioned in one side of the optical guide 11 so that a light as emitted from the light source 12 is transmitted and guided through the optical guide 11 and irradiated onto the entire display surface of the non-luminescent device. This sixth illumination method is disclosed in Japanese laid-open patent publication No. 10-123518.
The sixth illumination method has the following problems. The above mentioned position of the optical guide 11 causes reductions in transparency of the displaying light and in the efficiency in use of the light.
The seventh illumination method is as illustrated in FIG. 7 which is a fragmentary cross sectional elevation view illustrative of a seventh conventional non-luminescent display device, wherein a light source 22 is provided on a back surface of an optical guide plate 4. The optical guide plate 4 is plate-shaped and positioned so as to cover an entire of a displaying surface of the non-luminescent device. A light as emitted from the light source 22 is guided through the optical guide plate 4 and irradiated onto the entire display surface of the non-luminescent device. This seventh illumination method is disclosed in Japanese laid-open patent publication No. 7-333606.
The seventh illumination method has the following problems. The above mentioned position of the optical guide 11 causes reductions in transparency of the displaying light and in the efficiency in use of the light.
The eighth illumination method is as illustrated in FIG. 8 which is a fragmentary cross sectional elevation view illustrative of an eighth conventional non-luminescent display device, wherein a light source 9 and a prism 8 are provided. The prism 8 is positioned so as to cover an entire of a displaying surface of the non-luminescent device. The light source 9 is positioned in one side of the prism 8 so that a light as emitted from the light source 9 is transmitted and guided through the prism 8 and irradiated onto the entire display surface of the non-luminescent device. This eighth illumination method is disclosed in Japanese laid-open utility model publication No. 3-16128.
The eighth illumination method has the following problems. The above mentioned position of the prism 8 causes reductions in transparency of the displaying light and in the efficiency in use of the light.
In the above circumstances, it had been required to develop a novel non-luminescent display device free from the above problems.